CONCERN has mounted over Russia’s central bank governor after she suddenly cancelled an appearance at an exhibition without explanation. It comes amid circulating rumours that Elvira Nabiullina, 60, has undergone an unspecified surgery at the Kremlin. Russia's central bank has declined to comment on the rumours, Reuters reported. The Kremlin has also refused to comment on the surgery rumours, appearing annoyed at the question. “I do not consider this question appropriate at our conference call,” Putin’s spokesman told journalists today. "This is absolutely personal information about health and we have neither the scope nor the desire to comment on it."